This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A261431 #8 Mar 23 2017 04:15:25
%S A261431 1,0,1,2,9,24,175,720,7665,42560,436401,3628800,70215145,479001600,
%T A261431 7116730335,88966701824,1653438211425,20922789888000,457688776369825,
%U A261431 6402373705728000,145083396337080201,2457732174030848000,55735573291977790575,1124000727777607680000
%N A261431 Number of permutations p of [n] without fixed points such that p^n = Id.
%H A261431 Alois P. Heinz, <a href="/A261431/b261431.txt">Table of n, a(n) for n = 0..450</a>
%F A261431 a(n) = n! * [x^n] exp(Sum_{d|n, d>1} x^d/d).
%p A261431 with(numtheory):
%p A261431 A:= proc(n, k) option remember; `if`(n<0, 0, `if`(n=0, 1,
%p A261431 add(mul(n-i, i=1..j-1)*A(n-j, k), j=divisors(k) minus {1})))
%p A261431 end:
%p A261431 a:= n-> A(n$2):
%p A261431 seq(a(n), n=0..25);
%t A261431 A[n_, k_] := A[n, k] = If[n < 0, 0, If[n == 0, 1, Sum[Product[n - i, {i, 1, j - 1}] A[n - j, k], {j, Divisors[k] ~Complement~ {1}}]]];
%t A261431 a[n_] := A[n, n];
%t A261431 Table[a[n], {n, 0, 25}] (* _Jean-François Alcover_, Mar 23 2017, translated from Maple *)
%Y A261431 Main diagonal of A261430.
%Y A261431 Cf. A074759.
%K A261431 nonn
%O A261431 0,4
%A A261431 _Alois P. Heinz_, Aug 18 2015